1. Field of the Invention
The present invention concerns hair clips such as are used by women's hairdressers, for example.
2. Description of the Prior Art
Prior art hair clips (see for example documents FR-A-770 805, FR-A-755 662 and U.S. Pat. No. 2 201 719) usually have a first jaw operable by a first opening lever to which it is attached in a first intermediate connecting area and a second jaw operable by a second opening lever to which it is attached by a second intermediate connecting area. The first and second intermediate connecting areas are hinged together to allow the first and second jaws to pivot relative to each other about a transverse axis between an open position and a closed position. Spring means urge the first and second jaws into their closed position.
In these prior art hair clips the spring means include a spring constituted by an elastic metal wire coiled around the transverse pivot axis. A first end of the metal wire is extended radially away from the axis and bears against the inside surface of the first opening lever. The second end of the metal wire extends radially away from the axis and bears against the inside surface of the second opening lever. The spring is prestressed so that its two projecting ends urge the opening levers away from each other and so urge the jaws towards their closed position.
A first drawback of this type of design is that it requires the use of a metal wire formed into a coil spring with contiguous turns. The contiguous turns constitute a plurality of narrow slots or housings in which water and other liquid products can stagnate. In long-term use the metal wire can be corroded by the moisture and the various hairdressing products used.
A second drawback of a design of this kind is that the spring is necessarily prestressed in the direction from its open position towards its closed position, in order to apply sufficient clamping force to the clip. If the clip is heated, the ends of the spring can become embedded in the plastics material pivot arms and deform them if the plastics material is sufficiently softened by the heat. Thereafter the clip does not work properly.
A major drawback of this known design is a result of the manner in which such clips are used: when they are in place, in the hair, they usually show their posterior part, i.e. the part constituted by the two inside surfaces of the opening levers, by the posterior side of the hinge area and by the metal wire spring. This is particularly unattractive, especially as the metal wire structure of the spring is clearly visible and gives a somewhat mechanical appearance to a hairclip that should primarily be decorative and ornamental.
Another prior art hairclip described in document EP-A-0 516 564 has pivot means with interengaging male and female parts and special molded spring members having a generally U-shape profile with longitudinal branches and attachment parts. The fabrication and assembly of special shape molded spring parts increase the cost of manufacture.
The problem to which the present invention is addressed is that of eliminating the use of spring means constituted by a metal wire coil spring which may show on the posterior surface of the clip, in order to remove the drawbacks of the prior art clip designs. The aim is to produce a clip whose visible side is of pleasing esthetic appearance, the various parts of the clip being suitable for decoration whilst retaining their function of clamping the clip jaws in a satisfactory manner.
The clip design of the invention must also be suitable for manufacture at low cost and in particular assembly must be quick and simple.